DFARRAR> I am trying to store a couple numbers for each
DFARRAR> partition, in a subset of the partitions of my data
DFARRAR> set. Of course, one can accomplish this using a
DFARRAR> binary tree. (The first split is on
DFARRAR> inclusion/exclusion of the first object, and so
DFARRAR> on.) I can probably simulate a tree using vectors.
DFARRAR> (One vector gives the index of left child node,
DFARRAR> another the index of the right child node.)
DFARRAR> However, it seems like there must be a useful class
DFARRAR> associated with the clustering or recursive
DFARRAR> partitioning procedures, perhaps not out there for
DFARRAR> everyone to see. I poked around on the R page and
DFARRAR> didn't see anything that clearly met my needs very
DFARRAR> directly.

but maybe indirectly?

There's the "dendrogram" class in R, --> "?dendrogram", which
had been created with the aim to be a class that would allow
both regression/classification trees and hierarchical cluster
dendrograms to be represented. It's not just for binary trees,
and definitely much nicer to use than a "vector simulation"
version.

DFARRAR> I hope I would not have to learn
DFARRAR> recursive partitioning in R to find what I need.

(well, it may be worth your time to learn something about rpart
anyway; but you won't want to use it's representation of trees,
I think)